1. Field of the Invention
This invention relates to liquid measuring and metering devices and particularly to liquid dosaging devices.
2. Prior Art
In general, this invention is directed to a liquid metering or dosage device which includes an intermediate receptacle in communication with the valve block and a piston controlled burette also in communication with the valve block with means to provide a flow of fluid of a prescribed amount from the burette to the receptacle.
Such devices are used for precise portioning and delivering of liquids such as samples, reagents, etc. from liquid storage vessels to a further utilization vessel such as, for example, a reaction vessel. It has been known to utilize and automatically operated burette for precise liquid supply measurement with the burette having a variable stroke piston. (See for example, German Offenlegungsschrift No. 2,448,353). In such devices the measured liquid being ejected from the burette is conveyed to the receiving receptacle through a tube or hose line controlled by a valve block. Such device are disadvantageous for a number of reasons. The tube lines used constitute a large dead volume depending upon the tube diameter and length. Although such prior devices have attempted to maintain the dead volume as low as possible, this is not always achievable in such devices. Moreover, if it is desired to measure and inject into the receptacle a number of different liquids, separate burettes having separate liquid inlets and outlets are to be utilized. Thus, such setups can become quite expensive both in regards to material and time. For these reasons, such installations as automatically operated analysis apparatus are not economically and efficiently producable utilizing the prior art dosaging devices.